Why it’s easy to fall prey to confirmation bias
Will a no-deal Brexit cause chaos for Britain, or are the dangers being overblown? Is climate change real? We like to think we’re reasonable and open-minded, even when it comes to our most passionate beliefs. But research shows that this is rarely true. Once we’ve formed a belief, we believe that it is valid and well-founded; but, in reality, if any information challenges our views, we subconsciously ignore or devalue it.
This was demonstrated in a landmark 1979 study at Stanford by Charles Lord and colleagues. They presented undergraduates with two (fictional) studies, both with convincing statistics. One study claimed to prove capital punishment works as a deterrent, while the other concluded it had no effect on crime rates.
Before and after seeing the studies, participants were asked to give their views. Those who believed capital punishment is an effective deterrent rated the study supporting their views as credible, while rating the one that challenged their opinion as unconvincing. Those who were opposed to capital punishment reached the opposite conclusions.
This phenomenon has become known as “confirmation bias”. Further studies went on to demonstrate that our beliefs are rarely based on a deep understanding of a particular
issue. When it comes to belief, it seems we remember facts that support our world view, but ignore or reject information that runs counter to our opinions – and the more passionately we feel about an issue, the more this is so.
Not only do strong beliefs inhibit learning, they also cause us to make mistakes. Dan Kahan and colleagues at Yale gathered views on gun control from over 1,000 participants, then asked them to solve a mathematical problem. Some had to figure out whether a new skin cream was effective for treating rashes, while others were given the same statistics to decide whether a law banning concealed handguns reduced crime rates.
In the skin cream example, participants who were better at maths solved the problem more quickly and were right more often. However, when the subject was handguns, if the data challenged their opinion, people took longer to reach their conclusion and made more mistakes.
Given that belief so easily sabotages reason, how can you form opinions about emotive issues in a more balanced way? Deliberately seek out individuals who hold opinions different from your own and try to listen to their arguments nonjudgmentally. Read as much material as you can that challenges your views.
Explain in detail not only what you believe, but why you believe it. In their book The Knowledge Illusion,
Steve Sloman and Philip Fernbach cite a study that asked participants to rate their understanding of how everyday items such as a lavatory or a zipper work, then to explain in detail the mechanisms involved, then once again to estimate how well they understood them. Afterwards, participants rated their understanding more realistically.